Heat engine



Jan. 12, 1937. R; LEE I 2,067,453

' HEAT ENGINE Filed Jan. 30, 1935 w/ Messes Patented Jan. l2, 1937 Y attain ATT ll Claim.

The invention relates to heat engines of the hot-air type.

An object of the invention is to provide a hot-air engine of improved efficiency and of increased capacity for a given size.

Another object of the invention is to provide a hot-air engine in which the air onother gaseous working substance is regeneratively heated in such manner as to permit continuous ow of air and also to permit one regenerator to serve in common for a plurality of cylinders.

A further object is toprovide means for facilitating the starting of the engine and for replenishing the Working substance.

The invention further consists in the several features hereinafter described and claimed.

In the accompanying drawing, which illustrates one specinc form of heat engine embodying the invention,

Fig. l is a sectional elevation of a hot-air engine constructed in accordance with the invention, parts being shown schematically;

Fig. 2 is a top view of the engine, and

Fig. 3 is a sectional view taken generally along the line 3 3 of Fig. 1., the engine piston being shown in elevation.

In the drawing, i6 designates each of a plurality of cylinder members which are here shown to extend side by `side in parallel relation. Each cylinder member has an engine cylinder ll at one end and a pump cylinder l2 at the other end, the engine cylinder being preferably larger in diameter than the pump cylinder and preferably having a surrounding heat jacket for chamber il'. Each cylinder member has movable therein a piston member iii having a piston head or portion ll iitting in the engine cylinder li and a long piston portion l5 fitting in the pump cylinder l2. Power is delivered by each piston in any suitable manner, as by means of a pair of connecting rods i6 engaging a crank-shaft l'i and secured to opposite ends of a piston pin lil passing through the reduced portion of each piston and through opposite slots lil in the walls of the pump cylinder. In some instances the crank-shaft may have a fly-Wheel ll'. In the case of a two-cylinder engine, the cranks are 180 apart.

The passage of air or other gaseous working substance to and from each engine cylinder is controlled by any suitable mechanically operated valve means. For the purpose of illustration, the valve means are here shown to be poppet valves 2B and 2l for admission and exhaust, respectively, operated by a suitably driven cam shaft 22 (Cl. Gil- 59) rotating at crank-shaft speed and acting through push rods 23 and rocker arms 24.

The passage of the working substance to and from each pump cylinder is controlled by any suitable pressure-operated valve means, here exemplied by check valves 25 and 26 for admission and delivery, respectively.

The working substance, which is air or other gas, is conducted through one or more passages 21 of a heater 28, here indicated to have nre tubes 29, supplied with hot gases of combustion by a suitable burner 3G. The air and the hot gases of combustion ow through the heater in opposite directions, so that the air leaves the heater at the hottest part of the heater. The gases of combustion are discharged from the heater through a ue 3l which is in communication with the heat `jacket I l.

Hot air is conducted from the heater 28 tothe admission or inlet valves 20 of the engine cylinders by a conduit 32 having. a throttle valve 33. Beyond the throttle valve the conduit 32 is branched to lead to the engine cylinders.

A branched outlet conduit 36 conducts the air or other gas exhausted from the engine cylinders to one or more passages 35 of a suitable heat exchanger or regenerator 36. Tubes 3l in the heat exchanger conduct another stream of air at higher pressure to the heater 28. The high-pressure air passing to the heater and the low-pressure air from the engine cylinders ow through the heat exchanger in opposite directions, so that the air ilowing to the heater leaves the heat exchanger at the hottest part of the heat exchanger, and the air exhausted from the engine cylinders leaves the heat exchanger at its coolest part.

'Ihe cooled air from the heat exchanger flows through a branched conduit Sil'to the pressureoperated inlet valves 25 of the pump cylinders l2.

`The air may be further cooled in its passage through the conduit 38 by a cooler 39. The cooled air enters each pump cylinder on the suction stroke of the piston I3, and when compressed on the following stroke of the piston, the air passes through the delivery valve 26 and into a branch of a conduit i0 through which the air ows to the tubes 37 of the heat exchanger 36. Air is delivered from each pump cylinder l2V at a temperature not greater than the temperature of the low; pressure' air leaving the heat exchanger. Heat is preferably abstracted from the air undergoing compression in the pump cylinders, as by radiation from the cylinder walls.

` In order to compensate for any leakage and to facilitate starting, a valved air reservoir lll is provided to discharge air into the system through a conduit 42, preferably connected to the highpressure side of the system at the conduit 40. In addition', an air pump is provided to supplement the reservoir and preferably discharges into the high pressure side of the system. In the present instance, the air pump forms a part of the engine, anl annular compression chamber 43 being formed at the end of the engine cylinder II adjacent the pump cylinder I2. Air is conducted from the compression cylinder to the conduit 40' through a pipe 44 having a check valve 45. An unloader 46 of any well known construction connected to the compression chamber 43 prevents delivery of an excessive amount of air.

` When the engine isto, be started for the rst time or after the system has lost its pressure on standing, air or other suitable gas is admitted into the high-pressure side of the system'from the valved reservoir 4I, and the burner 30 is placed in operation. Hot air from the heater 28 flows through the conduit 32 to the engine cylinders and enters one of the engine cylinders II through its then open inletlvalve 20, causing the corresponding piston I3 to move on a power' stroke. The inlet valve 20 closes at part stroke,

and the airin the cylinder then expands duringv the rest of the stroke. At the end of the power stroke the exhaust valve 2| opens, and during the return stroke of the piston,the air is exhausted into the conduit 34 and enters the passage 35 of the heat exchanger 36, imparting-heat to the high-pressure air owingthrough the tubes 3'Iy to the heater 28. The cooled exhaust air leaving the heat exchanger flows through the conduit 38 to the inlet valves 25 ofv thepur'np cylinders, being further cooled in transit in the cooler 39. The cooled air is drawn into each pump cylinder I2 on the up-stroke of the piston. At the end of the return stroke of the piston head I4, the inlet valve 20 of the engine cylinder again opens and the power stroke is repeated. On the power stroke the air drawn into the'pump cylinder I2 is compressed, and when the pressure in the pump cylinder exceeds that in the conduit 4D air is discharged from the pump cylinder into this conduit and ows therethrough and through the kheat exchanger back to the heater, thus completing the cycle. After the few revolutions of the crank-shaft the pressures in the system reach their normal values,and thereafter adoltional air is admitted to the system only to compensate for leakage. The speed of the engine is controlled by the throttle valve 33, or by varying the air pressure, or by burner adjustment.

When the engine is stopped, a sufiicient amount 'of air is stored in the valved reservoir 4I to facilitate subsequent starting. The air capacity p of the heater 28 and heat. exchanger 3B is preferably'somewhat greater than that of the cylin- 10 ders, so that the pressures in the heater and heat exchanger remain substantially constant during the operation of the engine. The air entering' the engine cylinder II expands at approximately constant pressure during the rst par't of the 15 power stroke of the piston, and after the inlet val-ve 20l closes, the air in the cylinder expands .with dropping, pressure and temperature, a1,-

though some heat is absorbed by the expanding By providing a closed path for the working sube' stance, the minimum pressure can be above atgas fromv the hot walls of the piston and heat- 20 jacketed cylinder.

Inospheric pressure so as to increase the mean eiective pressure in the engine cylinders. The 2,5

closed system also permits the use of gases other than air, such as carbon dioxide or nitrogen. A suitable vapor, such as water vapor', may be added y to the working substance to improve heat con- 30 adjacent the smaller cylinder-forming an annular compression space with the larger end of said 40 piston, means for heating gas and for conducting the heated gas to said engine cylinder, means for conducting the gas exhausted from said engine cylinder to said pump cylinder, said cylinders and all of said means forming a closed system for the gas, the minimum pressure in said system being above atmospheric, and means supplied by said annular compression space for maintaining the minimum pressure in the system.

ROYAL LEE. 

